This invention relates to an apparatus and method for remotely sensing the alternating currants (AC) in a set of substantially parallel conductors from the magnetic fields generated by these currents in the vicinity of the conductors.
This invention relates to an apparatus and method for remotely sensing the alternating currents (AC) in a set of substantially parallel conductors from the magnetic fields generated by these currents in the vicinity of the conductors.
According to the present invention there is provided an apparatus for remotely sensing the currents flowing in a se of substantially parallel conductors carrying N independent AC crrents, the apparatus comprising N magnetic field sensors positioned to take mutually independent measurements of the magnetic field generated by the conductors and provide corresponding signals, and processing fews for deriving further signals, respectively corresponding to the conductor currents, based upon the sensor signals and the location and angular orientation of each sensor relative to each conductor.
Preferably, in the case where the further signals include harmonic components of the fundamental frequency of the conductor currents, the processing means includes means for deriving the harmonic components of the further signals, adjusting the amplitudes of the harmonic components to reduce any distortion produced by said harmonic components in the sensors, and recombining the adjusted frequency components with the fundamental frequency components to produce said further signals with reduced distortion.
Preferably the means for deriving harmonic frequency components of the sensor signals comprises fourier analysis means.
By xe2x80x9cpositioned to take mutually independent measurementsxe2x80x9d we mean that none of the sensors provides data which is substantially the same as or simply a linear combination of the data provided by the other(s). In practice this means that no two sensors have axes with the same angular orientation relative to the conductors and are in proximity when right projected onto a plane perpendicular to the conductors.
In this connection it is to be understood that the axis of a magnetic sensor is that direction relative to the sensor which, when orientated parallel to the lines of force of a fluctuating magnetic field passing through the sensor, would provide the maximum induced signal in the sensor for that magnetic field, and the plane of the sensor is a plane passing through the sensor normal to its axis.
Preferably the plane of each sensor is substantially parallel to the conductors.
The sensors are preferably coils, the plane of the coil being the plane through the geometric centre of the coil parallel to the turns of the coil and the axis of the coil being the direction through the coil centre normal to such plane.
The invention further provides a method for remotely sensing the currents flowing in a set of substantially parallel conductors carrying N independent AC currents, the method comprising positioning N magnetic field sensors to take mutually independent measurements of the magnetic field generated by the conductors and provide corresponding signals, and deriving further signals, respectively corresponding to the conductor currents, based upon the sensor signals and the location and angular orientation of each sensor relative to each conductor.